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COURSE CARE

Cool Weather Returns Disease Pressure Remains
February 27, 2015

Cool Weather Returns Disease Pressure Remains

By Adam Moeller, Agronomist
September 19, 2008

Cooler, wet weather with periodic days of sunshine and
moderate daily temperatures have been the general pattern
observed recently throughout most of the Northeast Region. The
cooler weather patterns are conducive to cool season turfgrass
growth, but disease pressure still remains. Diseases typically
associated with hot, humid weather like
Pythium
are behind us, but gray leaf spot (GLS) has been active
recently and may stay active until the first killing frost.
Surprisingly, a small outbreak of brown patch was recently
observed in southern New Jersey and was likely due to a
combination of recently fertilized turf (to promote core
cultivation recovery) and high nighttime temperatures and
humidity.

Dollar spot pathogens are quite active and will likely
remain so for a few more weeks. Numerous chemistries can be
used for dollar spot suppression, however, rotation between
active ingredients and tank-mixing is recommended. Diminishing
plant protectant supplies and/or expended budgets further
complicate later summer/early fall disease prevention
strategies. Reducing leaf wetness duration via dew removal
(mowing or dragging) is an invaluable mechanical practice for
limiting dollar spot disease pressure. Dollar spot also will be
more problematic on nitrogen deficient turf and outbreaks may
be an indication that previous fertilizer applications are at
the end of their release curve.

Disease pressure in September and October is certainly not
as high compared to July and August, however, organic matter
production via plant growth is accelerated and can increase
summer disease pressure. Topdressing should be continued during
the autumn months to dilute accumulating organic matter. Do
your best to topdress frequently this year to maintain root
zones with good soil physical properties. Ultimately, this will
reduce disease pressure and physiological stress potential.